In the manufacturing of a semiconductor device, the device is usually processed at many work stations or processing machines. The transporting or conveying of a partially finished device, or a work-in-process (WIP) part, is an important aspect in the total manufacturing process. The conveying of semiconductor wafers is especially important in the manufacturing of integrated circuit chips due to the delicate nature of the chips. Furthermore, in fabricating an IC product, a multiplicity of fabrication steps, i.e. as many as several hundred, is usually required to complete the fabrication process. A semiconductor wafer or IC chips must be stored or transported between various process stations in order to perform various fabrication processes.
A load port is used to handle not only semiconductor wafers but also different types of substrate to be processed such as liquid crystal display glass substrates and photomask glass substrates. Further, as a processing tool to which the substrate to be processed is transferred, various processing tools such as a manufacturing apparatus, visual inspection apparatus, electrical characteristic test apparatus are provided.
Recently, in order to enhance the manufacturing yield in a semiconductor manufacturing process, the diameter of wafers has increased and wafers with a diameter of 300 mm are used in addition to wafers with a diameter of 200 mm. Plural types of cassette are provided to receive substrates such as wafers. As some of the types of the cassette, cassettes for wafers with a diameter of 200 mm and cassettes for wafers with a diameter of 300 mm are provided. Further, as cassettes with different capacities, a small cassette capable of receiving 13 wafers and a large cassette capable of receiving 25 wafers are provided. As the shape of the cassette, an open-type cassette in which the eject port used to remove a wafer from the cassette is open and an integral-type cassette in which the eject port is covered with an open/close door are provided.